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CPS1999 Pranesh K. et al.
                  squares model, upper limits or lower limits of prediction interval are computed
                  by taking the coefficients as their corresponding estimated value plus or minus
                  standard error, i.e. using the equation,

                   = (23.5114 ± 0.8360) + (−0.0614 ± 0.0370).                                                         (7)

                  Similarly, the limits of fuzzy regression model are computed by the equation

                   = (23.5713 ± 0.4950) + (−0.0729 ± 0.0325).                                    (8)

                  The width of predicted intervals of fuzzy regression model is much smaller
                  than that of ordinary least squares model, which indicates the superiority of
                  fuzzy regression methodology.


































                                                              2
                    Figure 1: Ocean Heat content (in million km ) and Global Sea Ice Extent (in
                                                            2
                                                 million km ).

                  3.3. Error Analysis
                  To  make  performance  comparisons,  we  have  calculated  prediction  errors
                  denoted  by   =    −     and     =    −       and
                                  
                                                                       
                  corresponding  standardized  errors     =  ,  and     =
                                                                      
                                                                       
                    
                      , where   and     denote  the  standard  errors.    Further,  root  mean
                                    
                   
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